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Foraging areas of streaked shearwaters in relation to seasonal changes in the marine environment of the Northwestern Pacific: inter-colony and sex-related differences

Yamamoto, Takashi; Takahashi, Akinori; Oka, Nariko; Iida, Takahiro; Katsumata, Nobuhiro; Sato, Katsufumi; Trathan, Philip N.. 2011 Foraging areas of streaked shearwaters in relation to seasonal changes in the marine environment of the Northwestern Pacific: inter-colony and sex-related differences. Marine Ecology Progress Series, 424. 191-204. 10.3354/meps08973

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Abstract/Summary

As the spatial distribution of marine organisms is often affected by seasonal changes, pelagic seabirds may change their foraging areas in response to seasonal changes in the marine environment. Here, we examined the foraging area of streaked shearwaters Calonectris leucomelas, breeding at Sangan (SA) and Mikura Islands (MK), Japan, from spring to summer during pre-laying and incubation periods. Those colonies are located at the north and south of the Northwestern Pacific’s Kuroshio-Oyashio transition area where high seasonal temperature changes are observed, and where, consequently, birds may show comparable responses to such changes. Our results showed that streaked shearwaters from both colonies shifted their foraging areas northwards as the season progressed. The seasonal shift of foraging areas appeared to coincide with the movement pattern of pelagic fishes that migrate northward in association with the increase in water temperature. However, the pattern of seasonal movement differed between the 2 colonies; shearwaters from SA moved their foraging area along the coastal area of the Kuroshio-Oyashio transition, while those from MK moved along the Kuroshio Extension. Our results also indicated sex-related differences in this general pattern: females showed clear seasonal changes in foraging area, while males did not. During the pre-laying period males returned to the colony frequently to defend their nests or mates, and spent less time at sea. Our results suggest that streaked shearwaters changed their foraging areas in response to seasonal changes in the marine environment, although colony location and sex-related differences in reproductive roles may constrain the birds’ responses to seasonal change.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.3354/meps08973
Programmes: BAS Programmes > Polar Science for Planet Earth (2009 - ) > Ecosystems
ISSN: 0171-8630
Additional Keywords: Streaked shearwaters; Northwest Pacific; Seasonal change; Foraging; Kuroshio; Sex-related difference; Pre-laying
NORA Subject Terms: Marine Sciences
Biology and Microbiology
Ecology and Environment
Date made live: 26 May 2011 13:03
URI: http://nora.nerc.ac.uk/id/eprint/14023

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